'This white wilderness, this emptiness, is the North Pole,’ Sir David Attenborough intones in his rich, reassuring voice in the final episode of Frozen Planet.

'Beneath my feet and for 500 miles in every direction there are several metres of ice. But something significant is likely to happen at the North Pole soon. Chances are that sometime within the next few decades there will be open water here for the first time in human recorded history. The Arctic and the Antarctic are changing.’

We take the poles for granted. Forty per cent of our planet is covered in some form of ice, but it hasn’t always been that way. We take them for granted, and our knowledge of them is sketchy. People still frequently mistake the fact that polar bears are to be found in the north and penguins in the south; that Antarctica is a frozen continent and the Arctic a frozen ocean.

The BBC’s new series compares the poles throughout the seasons, combining extraordinary photography and technology with an emotional story­line told through its main characters: polar bears and Arctic wolves in the north, penguins and orcas in the south.

The extreme cold is not the problem for these animals, their challenge is the changing seasons. It took three years to make Frozen Planet and all the footage is new: orcas are seen hunting in groups by creating a wave that knocks a seal off the ice; we see frozen forests, the formation of a snowflake, the calving of a glacier and the birth of an iceberg. And there’s the first footage of a 'brinicle’, a stalactite of ice reaching to the sea floor that kills everything in its path as it freezes. The photography is epic and spectacular; every shot is mind-blowing. There is, as Attenborough told me, no dross.

The man behind this series is Alastair Fothergill. Fothergill has worked with Attenborough since 1988; he began at the BBC Natural History Unit (NHU) in 1983 and at the age of 32 he became its head.

He quit the post to go back into the field and make The Blue Planet (2001), followed by Planet Earth (2006), which had an audience of nine million, and is the highest-selling non-fiction DVD ever – worldwide. He is the executive producer on Frozen Planet, though in effect he is very hands-on, splitting the making of it with the series producer Vanessa Berlowitz. He now divides his time between the BBC and Disneynature, for which he has made two films, out next year, an unprecedented gesture by the BBC that shows the high regard in which he is held.

It was Fothergill who brought Attenborough to the North Pole for the first time in April last year. It was not easy. For a start, there is only a small window in which it is accessible: the Russians run a temporary camp there from the end of March, when the sun rises, only an annual event in the Arctic, to the end of April, when the ice is beginning to break up. They make a runway about 70 miles from the pole for aircraft to land, but to do that they need a tractor, which has to be dropped from a plane on to the ice, with parachutes attached to it. Sometimes it goes straight through the ice, and they have to start again.

There were six of the Frozen Planet team at the North Pole in April 2010: Attenborough, Fothergill, Berlowitz, the cameraman Gavin Thurston, the sound recorder Chris Watson and the logistics man Jason Roberts. As well as the Russians, there were also a couple of scientists, a blind man walking to the pole and an oligarch’s wife who arrived in Chanel furs just to have her photograph taken. There were also some very rich tourists, the sort who pay to ski or walk the last degree to the pole.

Attenborough was concerned by quite a large crack in the ice at the camp, but the Russians insisted that it wasn’t significant. Unfortunately the weather was terrible – a white-out – and nothing could be filmed, so the group were marooned in the tent for four days. 'Me and five stinky men,’ Berlowitz said lightly.

It was -40C outside and there was little to do – Berlowitz had a few natural history DVDs with her, Fothergill had a chess set, but Attenborough had forgotten to bring any music and had to watch several episodes of The Office on Thurston’s iPhone. 'We told stories,’ Fothergill says. 'David’s really good at that. Lots of us who work with him have heard them before, but they’re still bloody good. And we teased Vanessa. But by day four we were all going a bit stir crazy.’

The weather lifted and, finding the pole with a GPS, they got their footage of Attenborough standing on top of the world. After they had finished filming, Berlowitz tapped Fothergill on the shoulder and said, 'Happy birthday.’ He was 50.

Two hours after they took off again, the crack in the ice split 20m apart and the camp was sundered in two, separating the tents from the runway.

David Attenborough is the oldest man ever to go to the North Pole. 'You have to look after him now,’ Fothergill says. 'I mean he was 84. He can’t walk like he used to but my God he can write, and he can deliver. The old magic is absolutely there.’

Attenborough felt completely safe in the hands of his team, and he knew that every detail would have been considered. 'If Alastair asks me to do something, he will have worked it all out ahead: how far will I have to walk? Will there be anywhere to sit? He knows my limits. He is a great leader and people will follow him anywhere. He even looks like Shackleton. I can’t think of anybody better to take me to the North Pole.’

I first meet Fothergill at the airport in Resolute Bay in the Canadian Arctic in August 2010, next to an enormous stuffed polar bear. We are among a party of tourists who are about to board the Kapitan Khlebnikov, a Russian icebreaker leased by the polar tourism specialists Quark, on which Fothergill is lecturing. (The Frozen Planet team have enjoyed much support from Quark.)

He has brought along his two sons, Hamish, 15, and Will, 10, and is wearing a tweed waistcoat and cashmere jumper and looking for all the world as if he is about to take a stroll on the Norfolk Broads rather than embark on an expedition to the northernmost national park in the world. This is the last time the icebreaker will take the Tanquary Fjord route; having leased it to Quark for 20 years, the Russians want it back.

We will be on board for two weeks and it takes a while to get the feel of the ice, the measure of the unsetting sun. In my cabin, a rectangular porthole provides a framed view of unstoppable beauty for the entire trip. At midnight the sun streams through it, creating what looks like a perfect lightbox on the opposite wall. Other passengers are a mixture of Americans, Canadians and Europeans. I am one of the few taking a polar trip for the first time.

We land twice in the first few days, disembarking from the ship in Zodiac inflatables: on Beechey Island, where some members of John Franklin’s ill-fated search for the Northwest Passage were buried in 1845, and Devon Island, the largest uninhabited island in the world. We are on permafrost here and the ground is like clay, soft and muddy and lunar.

On the third day I am awoken by an announcement that there is a polar bear on the port side of the ship. There he is, larking about on the ice and sniffing the air, less than 50 yards from where the ship has parked. He disappears suddenly into a pool and emerges with a ringed seal in his mouth, bites off its head, then carries it off, leaving a train of dark red blood on the ice.

The passengers are all agog at this rare treat, Frozen Planet live, but I don’t realise just how rare it is until Fothergill says, through slightly gritted teeth, that the BBC has never been able to film a polar bear catching an adult ringed seal.

Later, sitting in the library, surrounded by books on the Arctic, Fothergill tells me about the genesis of Frozen Planet. It was the extraordinary success of Planet Earth and the ensuing feature film, Earth, that paved the way for the series. Fothergill is fascinated by the extraordinary annual change that occurs in the poles. 'The problems the animals face is the scenery – the world is literally melting beneath their feet and that is very visual and dynamic.’

The first episode opens with Attenborough laying out the facts and sorting out the geography, along with some extraordinary footage of the glaciers in Greenland. The next four episodes move into the seasonal storyline, starting with spring and comparing the changes in the poles and the effect they have on the animals. Programme 6, The Last Frontier, looks at how humans have adapted to the extreme environment, and finally On Thin Ice is an environmental special, examining the evidence of climate change, its impact on the poles and consequences for the rest of the world.

'What we’re doing that we’ve never done before in a landmark natural history series is to bring in the storytelling techniques of the Big Cat Diary, the emotional soap opera,’ Fothergill says. He believes strongly in storyboarding, rather than the old school of wildlife filmmaking which was to go out and see what you came up with. Fothergill and his team write the scripts almost as if they were making an ad or a fictional feature film, establishing the characters, a narrative and the sense of place, and the emotional heart of the story.

He works very closely with Berlowitz, a hugely experienced aerial director, who was a producer on Planet Earth. They wanted to mix the safe with the risky, with at least four sequences 'that will genuinely blow people away,’ Fothergill says. 'People in the UK have been spoilt as far as natural history is concerned because there is so much of it, and that presents a challenge.’

Another innovation is the technology, which has enormously improved since Fothergill made Life in the Freezer, a short series on the poles, in 1993. The team had substantial logistical support from the Royal Navy’s Antarctic patrol vessel HMS Endurance and the National Science Foundation (NSF) in America. And they had the Cineflex heligimbal, a camera that has had a vast impact on wildlife filmmaking, and was first used by the NHU in Planet Earth. The heligimbal is a gyro-stabilised camera mounted on a helicopter, plane or boat, which allows close-up photography from a long way away, so the noise won’t disturb the animals. The clip Fothergill showed us during one of his lectures, of a pack of Arctic wolves hunting a musk ox, was shot from 3,000ft up. And by using the Cineflex on a boat, they were able to film polar bears at stunningly close range.

There are some logistics that cannot be bought, and Fothergill approached the NSF, which runs the American Antarctic base at McMurdo in the Ross Sea, for help. He went to Washington, DC, to pitch to the head of logistics, the head of marketing and the head of science, but there wasn’t a smile out of them, and Fothergill thought that he had wasted his time. Then one of them said, 'My son did nothing but play computer games until I bought him a DVD of Planet Earth, and now that’s all he watches. And that’s why we’re going to support you.’

They were given 150 hours of helicopter time and six days of flight time in Twin Otter planes, millions of dollars worth of logistical support. In return, all the NSF wanted was 'outreach’ – for the American public to understand its work in the polar regions. The team flew the Twin Otters with the Cineflex up the Beardmore Glacier, the glacier that Captain Scott went to, which has never been filmed before.

They also had help from scientists from the University of California for the sequences of the orcas hunting minke whale and seals. The scientists had been satellite tagging the orcas, and were delighted to team up with Frozen Planet because they couldn’t afford a specially equipped boat like the BBC team had. 'They got four study papers out of it, we got our footage, and they used our footage to illustrate their work – we would not have been able to do it without each other,’ Fothergill says.

Juggling the budget, Fothergill had to make many tough decisions about which shoots to spend money on. Should they aim for the wolf hunt or try for the giant krill bait ball? They also had a time-lapse filming system called a motion-control rig built specially for the project. 'It cost a lot of money to develop and will probably provide 50 shots in the whole series, but they’re extraordinary because they show the seasonal change.’

There were casting decisions too, such as choosing the right penguin for the job. The Adélie, with its dinner suit and ridiculous rolling gait, got the part. It is the most southerly nesting of all penguins, so it suffers with the retreat and advance of the ice. And it is a comical penguin: there is a beguiling sequence in Spring, the second episode, when the male is collecting rocks for its nest to impress the female, and its neighbour sneaks up and repeatedly steals them for its own nest.

'More eggs, more eggs, the rangers are coming!’ shouts Philip, the German waiter, as three burly rangers come down the stairs for breakfast. We have reached Tanquary Fjord on Ellesmere Island, about 500 miles from the North Pole, part of Canada’s Quttinirpaaq (meaning topmost) National Park at 81.26º north. From April to the end of August every year, five rangers are stationed in sturdy canvas huts to monitor activity in the park and help visiting researchers (who fly out at a cost of $50,000). This is their last few days and they are delighted to come on board for some good food and new faces – they have seen nobody but each other and the odd scientist for four months.

We visit their home: much of the 14,585 sq mile park is glaciated with ice caps. There are caribou and more than 10,000 musk ox, white wolves and Arctic hare, and it is ridiculously beautiful and totally silent. Fothergill is a walking encyclopaedia of natural history; it’s like being escorted by, well, David Attenborough.

He points out the purple saxifrage – 'the most northerly flowering plant in the world’ – and a woolly caterpillar, which his son has unearthed, an amazing creature. 'It has glycerol in its blood, which is anti-freeze, so it can survive. In spring it starts feeding on the leaves of the dwarf willow. The dwarf willow then produces a toxin which is stimulated by chewing and after a while the caterpillar can’t eat it any more, so it has to close down for winter. It takes 14 winters before it’s big enough to pupate and finally come out as a moth. We filmed it for the Spring programme, in time lapse.’

The dwarf willow is the tallest tree in the Arctic – if it’s half an inch high and as thick as your thumb, it’s about 150 years old. Things grow slowly in the cold and dark.

Fothergill is explaining his three rules of wildlife filmmaking – 1) if you’re in the tent it will happen; 2) don’t waste time worrying about things you can’t control; and 3) it’s only television – when he suddenly grabs his binoculars and spots a snow goose, followed by a long-tailed jaeger, 'and there’s a red knot being chased by a ruddy turnstone – it’s all happening.’

He is the only member of the expedition without a camera. The next morning I see him pacing about on deck talking on the satellite phone to Berlowitz, who is shooting in Greenland. He is clearly envious. Greenland has the second biggest ice cap on the planet after Antarctica, a huge dome of ice two or three miles deep, flowing out from the summit to the coast. It has very active glaciers that are calving like crazy and the Frozen Planet crew has shot some spectacular footage of the retreating glaciers on a time-lapse camera. Greenland attracts a lot of scientists because everything is happening faster there; it’s become the centre of the northern hemisphere for work on climate change.

Berlowitz is filming the moulins, channels formed by lakes of turquoise blue meltwater spilling over. The channels carve their way through the ice and then plunge down a vertical shaft to the heart of the ice sheet, where they lubricate the junction between the ice and the rock floor, causing the glacier to move as much as 130ft a day. Yacubsharlem is the fastest flowing glacier in the world, and as it reaches the sea, great chunks will break off and form icebergs, an activity that obviously has serious implications for rising sea levels.

Near the end of our trip we go out in the Zodiacs to visit the bird cliffs on Prince Leopold Island. The vast cliffs look like something Antony Gormley could have designed, and function as a favela for birds. There is an established hierarchy: glaucous gulls at the top and northern fulmars, kittiwakes and guillemots stacked up underneath, and a strong smell of guano everywhere.

We disembark at Dundas Harbour, a grim little place where the Royal Canadian Mounted Police established sovereignty in the 1920s, and take a bracing walk across the tundra. 'Put this on, Will,’ says Fothergill, jamming a fur hat with earflaps on to his 10-year-old son’s head. 'Your mother will kill me if you get ill.’ Fothergill’s wife, Melinda, is not on this trip, because she doesn’t fly. They married in 1994; Melinda used to be a producer in the NHU. 'She hates flying. I never knew – she told me after the honeymoon, so I married her under false pretences. We go everywhere by train now.’

It is a good day for birds. Tramping along, binoculars in hand, Fothergill spots some eider ducks, then a grey gyrfalcon, long before anyone else can see them – we all peer hopelessly at the sky. He is pleased about the gyrfalcon; it was a good spot, but for someone who has seen falcons hunting Arctic hares, it’s a bit tame. 'That’s where she’s nesting,’ he says, pointing to a tiny white patch in the rock ledge, almost invisible to the naked eye.

Fothergill is a bird fanatic. He still gets excited, he says, when the swallows come back in April and he proposed to his wife in Norfolk with birds flying overhead. He grew up in London and Norfolk; his father was a schoolmaster at Harrow and the family would spend the long summer holidays in north Norfolk. 'My father would paint the house and listen to cricket on the radio and I cycled off to the wildlife reserve at Cley Marshes.’ When he was 12 Fothergill got an unpaid job there, cleaning the hides and helping out.

At Harrow, he had a biology teacher called Michael Thain who would take a group of proteges off on field trips. 'I remember he once organised an expedition to see the Caucasus black cock in Iran.’ It was Thain who inspired Fothergill’s initial ambition to be a research biologist. His mother wanted him to be a vet. 'Or something sensible like that. I had to promise her I’d never grow a beard, or wear white socks with sandals.’

He studied zoology at St Andrews then moved to Durham. While at Durham, as part of a BBC competition, Fothergill and his friends took a Super 8 camera on an expedition on the Okavango to look for the nesting ground of the pink-backed pelican. It was his first taste of natural history filmmaking. 'We travelled for five weeks in dugouts, sleeping on a different island every night, and walking with lions – it was one of the best experiences of my life. It wasn’t a very good film, but I thought, golly, this is a way to be paid to be with animals.’

The day after he finished university he went for an interview with the BBC Natural History Unit in Bristol. He was given a temporary job as a reporter on the BBC wildlife magazine because their researcher had broken his leg, then had a few other jobs on children’s natural history shows until in 1985 he became an assistant producer on The Really Wild Show.

The Really Wild Show was a completely new concept and it won Baftas three years running. Fothergill was learning on the job. 'They wouldn’t let me travel outside the UK; so I tried to film impossible things like wildcats in Scotland. The thing about children’s programmes is that there were no rules and you learn really quickly. I was doing live broadcasting, filming – everything.’

He did that for four or five years and then directed a Wildlife on One, which was when Attenborough remembers meeting him. 'It was a very useful series for filmmakers making their first film for the BBC,’ Attenborough says. 'It needed some kind of continuity, so I did all the narration. These young filmmakers would send me a script and I would edit it. One of these was a film on carmine bee-eaters. Lovely film. I wanted to change a few things, I always do, and normally some chap comes in and says, yes, yes, thank you very much. But in walked this young turk, Alastair. I made my suggestions, and he questioned them, and there was a sort of squaring-off, in which we were establishing what our relative positions were.’

They then worked together on Trials of Life in 1988, on which Fothergill was an assistant producer. 'That was amazing – trip after trip after trip. Very exciting, no email, no satellite phones – you never knew what was going to happen.’ In 1993 he made Life in the Freezer. 'It was a small series, but it kicked above its weight and it proved that the polar regions had a real power with the audience.’

The NHU in the early 1990s was the place to be if you wanted to make wildlife films. 'The people I work with now I’ve known since we were 20,’ Fothergill says. 'We all marry each other, have babies – it’s terribly incestuous but it’s lovely.’ The then head of the unit was leaving and Fothergill was asked to apply. He was unsure because his great love was being in the field, not behind a desk, and he was in the middle of making Life in the Freezer. 'But on a Sunday night I got a call telling me I had the job. I was living on the River Wye at the time and spent the whole night walking up and down, trying to decide and in the end I thought, I’d better do it. Then I went off to South Georgia thinking, what have I done?’

Attenborough was meeting him there. 'He said, right Alastair, we’re going for a walk.’ He knew exactly what I was going through – he had been the controller of BBC2 [which Attenborough left to go back to wildlife filming] and he said, do it.’

So he did – for five years, very successfully, although he had to pass up producing Attenborough’s Life of Birds, which he still regrets. He resigned his role to become the series producer of The Blue Planet, which was his idea, then there was the vastly successful series Planet Earth in 2006. The only criticism it received was that it was filmed through rose-tinted spectacles. 'The sort of programmes I make are not strongly environmental in their message. I think my skill is pure blue-chip natural history. Until Planet Earth, no one had filmed a snow leopard. I think there’s a real role in making people care. What I’m good at, if I’m good at anything, is the celebratory programmes; there are others who are doing fantastic environmental programming.’

Fothergill now has a deal to make three films for Disneynature, natural history films with a storyline. Two are coming out next year: African Cats, directed by Keith Scholey and produced by Fothergill, and the chimpanzee film Oscar, which he co-directed with Mark Linfield, Berlowitz’s husband, and filmed in the Ivory Coast and Uganda. Fothergill’s long-term collaborator George Fenton is doing the music. Fothergill cites Fenton and Attenborough as the two most inspirational people he has ever met.

A couple of months after the Arctic trip, I attend a music recording for Frozen Planet in London. The BBC orchestra, conducted by Fenton, is playing the music that he has written for the Autumn episode. Berlowitz and Miles Barton, the director of that segment, are there taking notes. Facing the orchestra is a large screen showing the bird cliffs of Svalbard, with the fledgling Brunnich’s guillemots learning to fly. The music is sculpted to the action on the screen: the baby birds taking off, faltering, plunging, crashing – and getting snapped up by the Arctic fox, attended by Attenborough’s humorous tone and Fenton’s light touch.

Fenton works his composition around the inflections of Attenborough’s voice ('it’s almost like a singer’s’), treating it like another instrument or a character. Fenton says Fothergill is very considerate towards the music, and will cut the film allowing for its presence. 'He also has a knack of knowing what appeals to a wider audience. The most important thing in producing, some would say, is to be able to raise money, but I think one of the qualities of a great producer is to protect the work, which he’s good at. There’s an alchemy with film – you can have the greatest of everything but you need the whole to become greater than the sum of its parts. Alastair is very collaborative, and he has the ability to put all the elements together and make everybody step up and enjoy it. It’s a rare thing.’

When I had last seen Berlowitz, at the BBC last summer, she had just returned from the South Pole. 'Flying in the Antarctic was my absolute dream,’ she says now, 'it was one of the reasons I wanted to do this series. With the help of the NSF, we went into places that probably hadn’t been seen by anyone since Scott, and it was really moving.’ Her baby son was 10 months old at the time, and Vanessa didn’t see him for 10 weeks. 'I would come back from flying over these incredible glaciers and then I’d Skype home and see my baby’s face…’

When she returned he didn’t recognise her and it took two weeks before he softened. 'Two weeks of hell. I nearly gave up at that point. But I’ve learnt from Alastair, who very much leads from the front – he’s passionate about being in the field – that it helps on a series like this, when you demand that people give up so much of their family life, that you are seen to do it as well. It was a high price to pay, but professionally it was the highlight of my career. It’s the only place on the planet where I have felt totally dwarfed and insignificant.’ Nowhere else, Berlowitz says, has she had such a strong sense of the fact that the planet is still in charge.

After 30 years of nature filmmaking, Fothergill still feels the same sense of wonder that he always has. 'In different stages of your life there are different pleasures. But the natural history thing never wanes for me. I’m as excited about it now as I was when I was 10. And now there’s another level, which is the satisfaction of all the logistics going right, and the pleasure of working with my team. And the final level is being able to enrich people’s lives. When we get it right, it’s not just any old telly. So much of TV is disposable, like fast food. We’re trying to do the fine dining, I suppose.’

Frozen Planet starts on October 26 at 9pm on BBC One, with a repeat on Sundays at 4.10pm. Jessamy Calkin travelled with the polar journey specialists The Ultimate Travel Company (020-7386 4646; theultimatetravelcompany.co.uk)